The trace log is composed of a series of messages. Each message logs a single OPC client- server event.

Note: The date/time and source are not shown in the following sample trace log for the purposes of clarity.

The sample trace log illustrates the sequence of messages logged with the trace level set to All. The OPC client initiated the following sequence of events (note that the OPC client used to generate the log is Data Access 1.0A compliant.)

1. The OPC client connected to the GagePort Mitutoyo OPC Server.

2. The client created an OPC group and called it Group1. The client created two advise sinks for Group1 for:

Receiving subscription notification callbacks (i.e. unsolicited updates from server for all items in Group1).

Receiving asynchronous write complete callbacks (i.e. notification from the OPC Server when an asynchronous write operation completed).

3. The client creates a second OPC group called Group2 with the similar advise sinks as Group1.

4. The client added an OPC group called Group1 called COM1.SIMPLE.VALUE.

5. Immediately the OPC Server began reporting to the client data change notifications (via a callback into the client).

6. The client proceeded to add two more points: COM2.GPFP.01 and COM2.GPFP.02.

7. Note that immediately after each new item was added, the number of items reported in the callback to the client increased. This is because the values are changing in the gages and being reported to the client at the requested OPC group update rate.

8. The client then removed the OPC group Group2. Prior to doing this, it disconnects the advise sinks previously setup.

9. The client then deletes the OPC group Group1. First it removes the item references from the group and then it disconnects the advise sinks.

10. Finally, the client disconnects from the OPC Server.

More information

OPC Connection Trace log.

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